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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-08-20 10:30:57 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-08-20 10:30:57 -0700 |
| commit | fb34438914188cc271d07a5fc2903489b6e9ab2d (patch) | |
| tree | 0cba437bc0e71e4014f0d47bc7c2a5780fe89294 | |
| parent | 0e665d5d1125f9f4ccff56a75e814f10f88861a2 (diff) | |
| parent | 0bce9c46bf3b15f485d82d7e81dabed6ebcc24b1 (diff) | |
| download | lwn-fb34438914188cc271d07a5fc2903489b6e9ab2d.tar.gz lwn-fb34438914188cc271d07a5fc2903489b6e9ab2d.zip | |
Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull a mutex fix from Ingo Molnar.
Fix the fastpath_lock failure contention flag for xchg-based mutexes.
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
mutex: Place lock in contended state after fastpath_lock failure
| -rw-r--r-- | include/asm-generic/mutex-xchg.h | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/include/asm-generic/mutex-xchg.h b/include/asm-generic/mutex-xchg.h index 580a6d35c700..c04e0db8a2d6 100644 --- a/include/asm-generic/mutex-xchg.h +++ b/include/asm-generic/mutex-xchg.h @@ -26,7 +26,13 @@ static inline void __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *)) { if (unlikely(atomic_xchg(count, 0) != 1)) - fail_fn(count); + /* + * We failed to acquire the lock, so mark it contended + * to ensure that any waiting tasks are woken up by the + * unlock slow path. + */ + if (likely(atomic_xchg(count, -1) != 1)) + fail_fn(count); } /** @@ -43,7 +49,8 @@ static inline int __mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *)) { if (unlikely(atomic_xchg(count, 0) != 1)) - return fail_fn(count); + if (likely(atomic_xchg(count, -1) != 1)) + return fail_fn(count); return 0; } |